Method of and apparatus for removing oil from a waste object

ABSTRACT

A waste object containing oil has a first opening formed therein at an upper portion thereof and a second opening positioned below the first opening. The first and second openings are connected to a recovery tank. Hot water of a predetermined temperature is held in the recovery tank and is caused to accumulate inside the waste object via the second opening. Oil that has floated upwards is recovered in the recovery tank via the first opening.

BACKGROUND OF THE INVENTION

1. (Field of the Invention)

The present invention relates to a method of removing oil as implementedprior to the breaking or dismantling of industrial waste objectscontaining oil, such as compressors, engines, or the like, and to anapparatus for effecting the same.

2. (Description of the Related Art)

Conventionally, after an industrial waste object made from iron, plasticor a combination of these, etc. has been broken up using a breakingmachine, or the like, it is recycled by separation and classification.

Since waste objects such as compressors, engines, or the like containoil, there is a danger of the oil catching fire and exploding if theyare put directly into a breaking machine in this state. Thus, it hasonly been possible to break up such products by low-temperature breakingin an inert gas atmosphere, which entails expensive apparatus andrunning costs. In general, it has been common to use manual dismantlingby fusing, which is inexpensive but dangerous.

However, the manual dismantling by fusing generates flames and involvesthe danger of fire or burns, the ambient atmosphere is degraded byproduction of smoke, and there are also limits on the processingcapacity of the operator. Accordingly, it has been necessary previouslyto remove oil from waste objects in an efficient manner, in order thatthey can be processed safely using a breaking machine, or the like.

SUMMARY OF THE INVENTION

The present invention has been developed to overcome the above-describeddisadvantages.

It is accordingly an objective of the present invention to provide amethod of and an apparatus for removing oil from industrial wasteobjects, whereby dismantling can be carried out safely without pollutingthe ambient environment, by removing oil efficiently from industrialproducts containing oil, prior to dismantling of the same in a breakingmachine, or the like.

In accomplishing the above and other objectives, a method according tothe present invention comprises the steps of: attaching an oil recoveryvessel to a first opening provided in an upper portion of a waste objectcontaining oil; injecting water into the waste object via a secondopening positioned below the first opening, thereby causing water toaccumulate inside the waste object and causing the oil inside the wasteobject to float upwards; and recovering the oil that floats upwards inthe oil recovery vessel.

Hot water, cleaning solution or water at room temperature is preferablyused as the water to be injected into the waste object to reduce theviscosity of oil contained therein or soften oil adhering thereto.

Advantageously, the second opening is connected to a recovery tank, andafter oil has been recovered in the oil recovery vessel, the oil andwater lying above the second opening is recovered in the recovery tank.

Conveniently, at least one of the first and second openings is athrough-hole formed in the waste object.

Another form of the present invention is a method comprising the stepsof: connecting a recovery tank to a first opening provided in an upperportion of a waste object containing oil and to a second openingpositioned below the first opening; injecting water of a predeterminedtemperature held in the recovery tank into the waste object via thesecond opening, thereby causing water to accumulate inside the wasteobject and causing the oil inside the waste object to float upwards; andrecovering the oil that floats upwards in the recovery tank via thefirst opening.

Advantageously, after oil has been recovered in the recovery tank, theoil and water lying above the second opening is recovered in therecovery tank via the second opening.

Conveniently, the first opening is connected to a vacuum pump, and theinside of the waste object is reduced to low pressure before water isinjected into the waste object.

Again conveniently, the first opening is connected to a compressed airsource, and after oil has been recovered in the recovery tank, the oiland water lying above the second opening is recovered in the recoverytank by supplying compressed air to the inside of the waste object.

A further form of the present invention is a method comprising the stepsof: connecting a heated fluid source and a recovery tank, respectively,to a first opening and a second opening provided in a waste objectcontaining oil; causing the oil inside the waste object to flow out viathe second opening, by supplying a heated fluid to the inside of thewaste object via the first opening; and recovering the oil dischargedfrom the second opening in the recovery tank.

It is preferred that steam be used as the heated fluid. In this case,condensate of steam supplied to the inside of the waste object is causedto accumulate inside the waste object.

Heated air may be used as the heated fluid. In this case, the secondopening is provided at the lowest point of the waste object, and oilinside the waste object, which has been reduced in viscosity by theheated air, is recovered in the recovery tank under its own weight.

An apparatus according to the present invention includes a recovery tankconnected to a first opening formed in an upper portion of a wasteobject and to a second opening positioned below the first opening, afirst pipe connecting the first opening to the recovery tank via a firstvalve, a second pipe connecting the second opening to the recovery tankvia a second valve, a pump provided in the second pipe, and a controllerfor controlling the first and second valves and the pump.

By this arrangement, when the second valve is opened and the pump isactuated, water of a predetermined temperature contained in the recoverytank is injected into the waste object via the second opening toaccumulate inside the waste object, thereby causing the oil in the wasteobject to float upwards. Such oil is recovered in the recovery tank viathe first opening by opening the first valve.

Advantageously, the apparatus further includes a third pipe connectingthe second opening and the recovery tank via a third valve, whereinafter oil has been recovered in the recovery tank, the oil and waterlying above the second opening is recovered in the recovery tank byopening the third valve.

Again advantageously, the apparatus further includes a vacuum pumpconnected to the first opening via a fourth valve, wherein beforeinjecting water into the waste object, the inside of the waste object isreduced to low pressure by opening the fourth valve.

The apparatus may include a compressed air source connected to the firstopening via a fifth valve, wherein after the oil has been recovered inthe recovery tank, the oil and water lying above the second opening isrecovered in the recovery tank by opening the fifth valve to supplycompressed air to the inside of the waste object.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objectives and features of the present inventionwill become more apparent from the following description of preferredembodiments thereof with reference to the accompanying drawings,throughout which like parts are designated by like reference numerals,and wherein:

FIG. 1 is a front view of a sealed compressor used as a work unitexample;

FIG. 2 is a piping system diagram of an oil removing apparatus accordingto a first embodiment of the present invention;

FIG. 3 is a timing chart of a case where oil removal is carried outusing the oil removing apparatus of FIG. 2;

FIG. 4 is a diagram similar to FIG. 2, but according to a secondembodiment of the present invention;

FIG. 5 is a block diagram illustrating the control of the oil removingapparatus of FIG. 4;

FIG. 6 is a timing chart of a case where oil removal is carried outusing the oil removing apparatus of FIG. 4;

FIG. 7 is a diagram similar to FIG. 2, but according to a thirdembodiment of the present invention;

FIG. 8 is a timing chart of a case where oil removal is carried outusing the oil removing apparatus of FIG. 7;

FIG. 9 is a diagram similar to FIG. 2, but according to a fourthembodiment of the present invention; and

FIG. 10 is a timing chart of a case where oil removal is carried outusing the oil removing apparatus of FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This application is based on an application No. 10-215209 filed Jul. 30,1998 in Japan, the content of which is incorporated hereinto byreference.

FIG. 1 shows a sealed compressor W forming an industrial waste object,which includes a sealed container 2 holding an electric motor andcompressor elements, and a gas-liquid separator 4 juxtaposed with thesealed container 2. The gas-liquid container 4 is coupled to an inletpipe 6, and the sealed container 2 is coupled to a discharge pipe 8. Thesealed compressor W contains oil for lubricating the compressor elementsduring operation, and if the sealed compressor W were to be introducedinto a breaking machine in this state, there is a danger that the oilwould catch fire and explode.

The implementation of the method of removing oil according to thepresent invention is described below, using the sealed compressor Whaving the foregoing composition as a work unit example.

Embodiment 1

FIG. 2 shows an oil removing apparatus according to a first embodimentof the present invention, and FIG. 3 is a timing chart of a case whereoil is removed.

As shown in FIG. 2 and FIG. 3, the work unit W is first set and clamped(fixed) in a predetermined position, and a through-hole 10 of φ6-8, forexample, is formed by drilling, punching, or the like, in an upperportion of a cylindrical shell forming the sealed container 2, which isa part of the work unit W. Thereupon, an oil recovery drum 14 having avalve 12 is connected to the discharge pipe 8, and an oil and hot waterrecovery tank 18 accommodating a heater 16 and positioned in thevicinity of the work unit W is connected via pipes 20, 22 to thethrough-hole 10 in the sealed container 2. A hot water pump 24 and avalve 26 are installed on the course of the pipe 20, while a valve 28 isinstalled on the course of the pipe 22. A level sensor 30 is attached tothe oil recovery drum 14 for detecting the level of hot water or oilcontained therein.

The heater 16 is already switched on prior to the formation of thethrough-hole 10 in the sealed container 2, and water previously storedin the oil and hot water recovery tank 18 is heated to a predeterminedtemperature by means of ON/OFF control by a thermostat (not shown).

In this state, an opening of the inlet pipe 6 is closed and the valve 12is opened. After a predetermined time period T1 has passed, the valve 26is opened and the hot water pump 24 is actuated, whereupon the hot waterheld at the predetermined temperature by the heater 16 passes from theoil and hot water recovery tank 18 to the sealed vessel 2. When thewater has passed and it is detected by the level sensor 30 that the hotwater or oil inside the oil recovery drum 14 has reached a predeterminedlevel, the hot water pump 24 is halted and the valve 26 is closed.

If this state is maintained for a predetermined time period T2 (forexample, 1 second-10 seconds), then practically all of the oil remainingin the sealed container 2 will be heated by the hot water and theviscosity thereof will fall (it will become more fluid), and hence theoil will gradually float upwards in the sealed container 2, beingrecovered in the oil recovery drum 14 and accumulating in the upperportion thereof.

After a predetermined time period T2 has elapsed, the valve 12 isclosed, and the oil recovery drum 14 is separated from the sealedcontainer 2, whilst the valve 28 is opened for a predetermined timeperiod T4 such that the hot water located above the through-hole 10 andcontaining a quantity of oil is recovered in the oil and hot waterrecovery tank 18.

The oil inside the oil recovery drum 14 separated from the sealedcontainer 2 is further separated into an oil component and watercomponent by an oil/water separating device (not shown), via a recoverydevice (not shown). The separated oil component is further deaerated bya vacuum deaeration device, dust and moisture is separated therefrom,and it is then reused as lubricating oil, fuel oil, or the like.

The hot water in the upper portion of the through-hole 10 is recoveredin the oil and hot water recovery tank 18. After the valve 28 is closed,the work unit W which is filled with water is removed and introducedinto a breaking machine. Since almost all of the oil is removed from thework unit W and the work unit W is filled with water, temperature riseduring breaking is suppressed and there is no danger of fire orexplosion.

Embodiment 2

FIG. 4 shows an automated apparatus for extracting oil according to asecond embodiment of the present invention.

In the oil extracting apparatus illustrated in FIG. 4, since theposition in which the through-hole 10 is formed and the connectionrelationship between the work unit W and the oil and the hot waterrecovery tank 18 are the same as those in the oil extracting apparatusillustrated in FIG. 2, only the points of difference are describedbelow.

A discharge pipe 8 attached to a sealed container 2 is connectedrespectively, via a pipe 36 and pipe 38, to a vacuum pump 32 andcompressed air source 34. A valve 40 and an oil recovery tank 42 areinstalled on the course of the pipe 36, while a valve 44 is installed onthe course of the pipe 38. The discharge pipe 8 is also connected via apipe 46 to an oil and hot water recovery tank 18. A valve 48 isinstalled in the pipe 46, and a hot water detector 50, such as a reedswitch, is installed between the valve 48 and discharge pipe 8.

In FIG. 4, numeral 52 is a compressed air pressure detector attached tothe pipe 38, numeral 54 is a vacuum state detector attached to the oilrecovery tank 42, and numeral 56 is a hot water temperature detectorattached to the oil and hot water recovery tank 18.

As shown in FIG. 5, a heater 16 provided in the oil and hot waterrecovery tank 18, a hot water pump 24, vacuum pump 32, valves 26, 28,40, 44, 48 and various detectors 50, 52, 54, 56 are connectedelectrically to a controller 58, which performs various controloperations.

Next, the action of the oil removing device in FIG. 4 is described withreference to the timing chart illustrated in FIG. 6.

Similarly to the first embodiment, the work unit W is first set andclamped in a predetermined position, and a through-hole 10 of φ6-8, forexample, is made by drilling, punching, or the like, in the upperportion of the cylindrical shell forming the sealed container 2.Thereupon, the pipe 36 leading to the vacuum pump 32, the pipe 38leading to the compressed air source 34, and the pipe 46 leading to theoil and hot water recovery tank 18 are connected to the discharge pipe8. The oil and hot water recovery tank 18 is connected to thethrough-hole 10 in the sealed container 2 via pipes 20 and 22.

The heater 16 is already switched on prior to formation of thethrough-hole 10 in the sealed container 2, and the water inside the oiland hot water recovery tank 18 is heated by the heater 16 and thetemperature thereof is detected by a hot water temperature detector 56.A signal indicating the detected temperature is transmitted to thecontroller 58 and the water in the oil and hot water recovery tank 18 isheld at a predetermined temperature (for example, 50-65° C.) by means ofthe controller 58 performing ON/OFF control of the heater 16 on thebasis of the temperature signal.

On the other hand, the oil recovery tank 42 is reduced to a vacuum bythe vacuum pump 32, and when the vacuum state detector 54 detects apredetermined vacuum state after the pipe connections to the work unit Whave been established, it transmits a signal to this effect to thecontroller 58, which causes the valve 40 to open.

After a predetermined time period T1 (for example, several seconds,) haselapsed, the valve 40 is closed, and simultaneously with this, the hotwater pump 24 is activated and the valve 26 is opened. Thereupon, sincethe work unit W is in a reduced pressure state, hot water supplied fromthe oil and hot water recovery tank 18 by means of the hot water pump 24accumulates rapidly inside the work unit W. When hot water accumulatesinside the work unit W, the viscosity of the oil remaining inside thework unit W is reduced by the hot water, and this oil gradually floatsupwards. When the hot water detector 50 confirms that hot water or oilis overflowing from the work unit W, it transmits a signal to thiseffect to the controller 58, which causes the valve 48 to open.

When the valve 48 is opened, the oil which has been reduced in viscosityand has become more fluid is recovered in the oil and hot water recoverytank 18 via the valve 48. When a predetermined time period T2 (forexample, several seconds) has elapsed after opening the valve 48, boththe valve 48 and valve 26 are closed, and the hot water pump 24 ishalted. In this state, if the compressed air pressure as detected by thecompressed air pressure detector 52 is above a predetermined value (forexample, 3.5 kg/cm²), then the detector 52 sends a signal to this effectto the controller 58, which causes the valve 44 and valve 28 to open.Consequently, the hot water containing oil accumulated in the portion ofthe work unit above the through-hole 10 is recovered rapidly in the oiland hot water recovery tank 18 via the valve 28 under the pressure ofthe compressed air supplied via the valve 44. Once the valve 44 has beenopened for a predetermined time period T3, it is closed and after afurther predetermined time period T4 has elapsed, the valve 28 isclosed.

Thereupon, the work unit W containing water in the portion thereof belowthe through-hole 10 is detached and introduced into a breaking machine.

Similarly to the first embodiment, the oil recovered in the oil and hotwater recovery tank 18 is further separated into an oil component andwater component by an oil-water separating device, via a recoverydevice. The separated oil component is further deaerated by means of avacuum deaeration device, and dirt and moisture are removed, whereuponit is reused.

In the embodiment described above, the vacuum pump 32, compressed airsource 34, and associated piping are not specifically necessary, andthese elements may be omitted.

Moreover, in this embodiment and the first embodiment, hot water wasused as the recycling water, but it is also possible to use a cleaningsolution containing a cleaning agent at a predetermined temperature. Ifthe ambient temperature is high, then the cleaning solution or water atroom temperature may be used directly without heating.

Moreover, the position of the through-hole 10 was set in the upperportion of the cylindrical shell forming the sealed container 2, but thethrough-hole may also be provided in another position, provided thatthis position allows a certain amount of water to accumulate inside thesealed container 2. It is also possible to provide two or morethrough-holes in the sealed container 2, sealing off the discharge pipe8 and connecting the pipes 20, 22, 36, 38, 46 independently.Furthermore, rather than providing any through-holes, it is alsopossible to utilize the openings of the inlet pipe 6 and the dischargepipe 8.

Embodiment 3

FIG. 7 shows an oil removing apparatus according to a third embodimentof the present invention, and FIG. 8 is a timing chart of an oilremoving process.

As illustrated in FIG. 7 and FIG. 8, a work unit W is first set andclamped in a predetermined position, and a through-hole 10 of a φ6-8 isformed by drilling, punching, or the like, in a lower portion of thecylindrical shell, which forms a part of the work unit W. Thereupon, asteam supply source 60 is connected via a pipe 62 to a discharge pipe 8,and a pipe 64 forms a branching junction along the course of pipe 62. Avalve 66 is attached to the pipe 62 and a valve 68 connected to the airis attached to the pipe 64.

On the other hand, an oil and hot water recovery tank 18 provided in thevicinity of the work unit W is connected to the through-hole 10 in thesealed container 2 via a pipe 70. The opening of the inlet pipe 6 issealed off.

In this state, if steam is supplied into the work unit W from the steamsupply source 60 by opening the valve 66, whilst also opening valve 72,then the oil remaining inside the work unit W will be heated by thesteam, the viscosity thereof will fall, and the oil will accumulate in abottom portion of the work unit W. When valve 66 has been held open fora predetermined time period T1, a portion of the steam will condense,forming hot water, which accumulates in the lower portion of the workunit W with the oil. Consequently, the oil floats to the top of the hotwater, and is recovered in the oil and hot water recovery tank 18 viathe pipe 70.

When a predetermined time period T1 has elapsed, the valve 66 is closedand the valve 68 is opened, thereby allowing the oil to continue to berecovered in the oil and hot water tank 18, whilst releasing thepressure inside the work unit W externally, via the valve 68. When thevalve 72 has been opened for a predetermined time period T2, it isclosed along with the valve 68.

The pipes 62, 64 are then detached from the discharge pipe 8 and thepipe 70 is removed from the through-hole 10, whereupon the work unit Wis introduced into a breaking machine.

The subsequent processing of the oil recovered from the oil and hotwater recovery tank 18 is similar to that in the first and secondembodiments, and hence description thereof is omitted here. Moreover, itis also possible to provide two or more through-holes in the sealedcontainer 2, the discharge pipe 8 being sealed off and the pipes 62, 64and 70 being connected independently. Moreover, rather than providingany through-holes, it is also possible to utilize the openings of theinlet pipe 6 and the discharge pipe 8. Furthermore, instead of steam,pressurized hot water or cleaning solution may be used, and if theambient temperature is high, pressurized water at room temperature maybe used.

In the present embodiment, since the work unit W contains accumulatedwater when it is introduced into a breaking machine, there is littletemperature rise during breaking, and since the oil content thereof issmall, there is little danger of fire or explosion.

Embodiment 4

FIG. 9 shows an oil removing apparatus according to a fourth embodimentof the present invention, and FIG. 10 is a timing chart of an oilremoving process.

This embodiment is similar to the third embodiment, but differstherefrom in that heated air or steam is used as a medium to be suppliedto the work unit W and in that a through-hole 10 is formed in the centerof the lower part of the shell (lowest point).

Therefore, in the present embodiment, there is no accumulation of waterin the work unit W and the oil is recovered in the oil and hot waterrecovery tank 18 under its own weight. The further composition andaction of this embodiment is the same as the third embodiment, and hencedescription thereof is omitted here. Moreover, instead of heated air orsteam, it is possible to use pressurized hot water or cleaning solution.If the ambient temperature is high, then pressurized water at roomtemperature may be used. It is also possible to provide two or morethrough-holes in the sealed container 2, the discharge pipe 8 beingsealed off and the pipes 62, 64 and 70 being connected independently.

The first to fourth embodiments described above relate to a case where asealed compressor is used as the work unit W, but the present inventioncan of course be applied to other sealed objects containing oil, such asengines, or the like.

Being constituted as described above, the present invention has thefollowing merits.

According to the first aspect of the present invention, water is causedto accumulate inside the waste object by injecting water via a secondopening positioned below the first opening, and the oil that floatsupwards is recovered in an oil recovery vessel via the first opening.Accordingly, the oil is gathered reliably into the oil recovery vessel,the oil becoming separated from the water due to the difference inspecific gravity, and hence oil can be recovered with good efficiency.

Moreover, since a second opening is connected to the recovery tank, andafter the oil has been recovered, the oil and water lying above thesecond opening is recovered in the recovery tank, virtually no oilremains in the waste object prior to dismantling. Thus, the waste objectcan be dismantled safely.

Furthermore, since a through-hole formed in the waste object is used forat least one of the first and second openings, it is possible to set theamount of water accumulating inside the waste object according to theposition in which the through-hole is formed, and hence temperature riseduring dismantling of the waste object can be suppressed appropriately.

Also, since water is caused to accumulate inside the waste object byinjecting the water in the recovery tank via the second opening, whilstthe oil that has floated upwards is recovered in the recovery tank viathe first opening, it is possible to effectively recover oil that hasbeen separated from the water due to the specific gravity difference,without ambient dispersal of oil.

Moreover, since the inside of the waste object is reduced to a lowpressure before injecting water into the waste object, water accumulatesrapidly therein and oil recovery can be carried out with goodefficiency.

Also, after oil has been recovered, the oil and water lying above thesecond opening is recovered rapidly in the recovery tank by supplyingcompressed air to the inside of the waste object. It is, therefore,possible to raise the efficiency of oil recovery and increase the safetyof dismantling.

If a heated fluid is supplied to the inside of the waste object via thefirst opening to reduce the adhesion of the oil inside the waste objectand to make the oil more fluid, it is possible to recover oil reliably,without contaminating the ambient atmosphere, using a simplecomposition.

Furthermore, since steam is used as a heated fluid and water condensedfrom the steam supplied to the waste object accumulates inside the wasteobject, it is possible to suppress temperature rise during dismantlingof the waste object.

The oil inside the waste object can be recovered in the recovery tankunder its own weight by reducing the viscosity thereof using heated air.In this case, oil recovery can be effectively carried out in anextremely simple manner.

In the oil recovering apparatus according to the present invention, whena second valve is opened and a pump is actuated, water in a recoverytank is caused to accumulate inside the waste object via a secondopening and to float upwards. When a first valve is opened, the oil thathas floated upwards is recovered in the recovery tank via a firstopening. Accordingly, it is possible to recover oil which has beenseparated from water by means of their difference in specific gravity,efficiently, without oil being dispersed into the ambient environment.

Furthermore, since the oil and water lying above the second opening isrecovered in the recovery tank by opening a third valve, after oil hasbeen recovered, virtually no oil remains in the waste object beforedismantling. It is, therefore, possible to dismantle the waste objectsafely.

Moreover, since the internal pressure of the waste object is reduced byopening a fourth valve before causing water to accumulate inside thewaste object, it is possible to fill water into the waste objectrapidly, and hence oil recovery can be carried out efficiently.

Also, after oil has been recovered, the oil and water lying above thesecond opening is recovered rapidly by supplying compressed air to theinside of the waste object by opening a fifth valve. Accordingly, it ispossible to achieve good efficiency of oil recovery and safe dismantlingof the waste object.

Although the present invention has been fully described by way ofexamples with reference to the accompanying drawings, it is to be notedhere that various changes and modifications will be apparent to thoseskilled in the art. Therefore, unless such changes and modificationsotherwise depart from the spirit and scope of the present invention,they should be construed as being included therein.

What is claimed is:
 1. An apparatus for removing oil from a waste objectthat has a first opening formed in an upper portion thereof and a secondopening positioned below the first opening, said apparatus comprising: arecovery tank connected to the first and second openings; a first pipeconnecting the first opening to said recovery tank and having a firstvalve; a second pipe connecting the second opening to said recovery tankand having a second valve; a third pipe connecting the second openingand said recovery tank and having a third valve: a pump provided in saidsecond pipe; and a controller for controlling said first and secondvalves and said pump, wherein water of a predetermined temperaturecontained in said recovery tank is injected into the waste object viathe second opening to accumulate inside the waste object by opening saidsecond valve and by actuating said pump, thereby causing the oil in thewaste object to float upwards; wherein the oil that has floated upwardsis recovered in said recovery tank via the first opening by opening saidfirst valve; and wherein after oil has been recovered in said recoverytank, the oil and water lying above the second opening is recovered insaid recovery tank by opening said third valve.
 2. The apparatusaccording to claim 1, further comprising a vacuum pump connected to thefirst opening via a fourth valve, wherein before injecting water intothe waste object, the inside of the waste object is reduced to lowpressure by opening said fourth valve.
 3. The apparatus according toclaim 2, further comprising a compressed air source connected to thefirst opening via a fifth valve, wherein after the oil has beenrecovered in said recovery tank, the oil and water lying above thesecond opening is recovered in said recovery tank by opening said fifthvalve to supply compressed air to the inside of the waste object.